assume cs:codesg, ds:datasg

datasg segment
    db 'welcome to masm.'
    db '................'
datasg ends

codesg segment
start:
    mov ax, datasg
    mov ds, ax

    mov si, 0
    mov di, 16
    mov cx, 16

s:
    mov al, ds:[si]
    mov ds:[di], al
    inc si
    inc di
    loop s

    mov ax, 4c00H
    int 21H
codesg ends

end start